I'm sure I've read a fic where he had a last name, but I can't remember what it was or if Lois actually ever mentioned his last name in the show.

I'm just curious if he actually had one or if people just take creative liberties and give him one they made up.

I think they just take liberties. I was reading through the pilot script again last night (scanning for Lois's nicknames for Clark) and I remember her telling him about Claude, but not that she said his last name.

Spanx, V!

I need to find a good last name for him then so he can be hunter and... oh, you'll see

Well, he's French and you're Canadian (or at least have lots of access to Canadians, who've been taught French), I'm thinking you could have fun with it.

This is true! We start taking French classes in, I think, the third grade, and it's mandatory all the way up through 9th grade. Regardless, I really didn't retain much because my attendance was terrible lol.